This invention relates generally to orthoses for providing assistance in walking. More particularly, the present invention relates to an improved knee joint for such an orthosis.
An orthosis is a brace or other orthopedic device that is applied to a segment of a human body for the purpose of assisting in the restoration or improvement of its function. Orthoses can provide assistance in walking to persons having any of several types of walking disability. One known type of orthosis is a knee/ankle/foot orthosis which controls the motion and alignment of a knee and an ankle when a person attempts to walk. Such orthoses can be made of molded plastic materials or of metal and leather parts, Various knee and ankle joints can be added to achieve the desired function.
Typical reasons for wearing such an orthosis include stroke, brain injuries, spinal cord injury and post-polio treatment. A person who is not able to move his leg in a functional manner to ambulate, must wear a knee/ankle/foot orthosis to stabilize his leg and allow for ambulation. It has been found that for people with weak knee joints, a locking mechanism is necessary in order to lock a calf supporting orthosis to prevent movement in relation to a thigh supporting orthosis, thereby allowing the person to walk, albeit stiff legged.
There are many types of knee joints used on such orthoses. However, all the known joints which lock during ambulation are manual. In other words, when a patient is using the orthosis, he has a choice of walking with his leg locked in extension or in a free swing. If the patient chooses the locked position, he is forced to walk stiff legged. However, for some people, flexing at the knee during walking would result in a buckling of the person""s leg. Therefore, walking stiff legged is much preferable to being not able to walk at all. Of course, a movement of the calf orthosis in relation to the thigh orthosis is necessary when the person decides to sit down.
As far as is known, there are no knee joints currently on the market which have the ability to automatically lock and unlock without direct manual patient intervention.
Accordingly, it has been considered desirable to develop a new and improved orthosis knee joint which would overcome the foregoing difficulties and others while providing better and more advantageous overall results.
In accordance with the present invention, there is provided an orthosis for assistance in walking.
More particularly in accordance with this aspect of the invention, the orthosis includes an orthosis system which comprises a foot plate including at least one pressure sensor that senses the pressure exerted by a patient""s foot on the foot plate, a circuit connected to at least one pressure sensor in the foot plate and a knee joint which is selectively locked and unlocked by the circuit. To this end, the knee joint is electrically operated.
In accordance with the present invention, a selectively lockable orthotic joint is provided. The selectively lockable orthotic joint includes at least one pressure sensor which can be used to sense a person""s weight or a portion thereof, and may be a sensor to be associated with a person""s foot, for example. An electronic circuit is provided that is associated with the pressure sensor for generating a control signal indicative of pressure or weight sensed by the sensor. At least one mechanical orthotic joint that incorporates a locking mechanism is included which orthotic joint can be selectively locked and unlocked in response to the control signal.
More particularly, the mechanical orthotic joint of the selectively lockable orthotic joint invention includes an energizable electromagnetic coil, a spring washer deflectable in an axial direction when the electromagnetic coil is energized and an arrangement of first and second plates. The first plate has a face or an operative surface composed of a plurality of spaced teeth. The second plate also has a face or an operative surface having a plurality of spaced teeth that are complementary to the plurality of spaced teeth of the first plate. The second plate is mounted so that it is deflectable in an axial direction such that the plurality of spaced teeth of the second plate can engage the plurality of spaced teeth of the first plate when the electromagnetic coil is energized. The engagement of the first and second plates locks movement of the orthotic joint in at least one direction when the first and second plates are engaged.
In accordance with one embodiment, the first and second plates are complementary and each comprise ratchet plates allowing the orthotic joint to move only in one direction when the joint is in a locked position. More specifically, in one embodiment, when unlocked the orthotic joint is movable in a flexion direction and an extension direction and when the orthotic joint is locked, it is movable only in the extension direction.
The first and second plates may comprise a low hysteresis magnetic material.
In accordance with another aspect of the present invention, a method for selectively locking and unlocking an orthotic joint is provided. One embodiment locks the orthotic joint to permit movement only in the extension direction.
In accordance with the method, an orthotic joint of the type previously described is utilized. Pressure is sensed by the pressure sensor and an electronic control signal is generated with the electronic circuit that is indicative of pressure sensed by the pressure sensor. In response to the electronic control signal, the orthotic joint locks through its locking mechanism.
One advantage of the present invention is the provision of a knee joint which allows patients, who are currently walking stiff legged with a locked knee joint in a knee/ankle/foot orthosis, to walk with a more normal gait.
Another advantage of the present invention is the provision of an orthosis which will make sitting and standing much safer and easier for any patient forced to manually unlock his knee joint.
Still another advantage of the present invention is the provision of an orthosis system which senses the pressure placed by a patient""s foot on a foot plate of the orthosis and can automatically trigger a knee joint of the orthosis to lock and unlock. The knee joint will be locked when pressure is placed by the patient""s foot on the foot plate. It will be unlocked when the patient""s foot no longer exerts pressure on the foot plate.
In accordance with another aspect of the invention, a selectively lockable orthotic joint is provided. The selectively lockable orthotic joint includes an electronic circuit for providing at least one control signal indicative of a value. At least one mechanical orthotic joint is provided that includes a locking mechanism that is in communication with the circuit. The locking mechanism can be selectively locked and unlocked in response to the control signal. The control signal provided by the electronic circuit can originate from a variety of sources other than by sensing pressure or weight. For example, the control signal can originate from EMG signals in leg muscles, from EEG signals, from a sensor that detects distance between the ground and the bottom of a shoe or other article, such as a cane, for example. In addition, a controller could be provided for operation by the user, such as a joy stick or other type of switch in order to generate or otherwise provide the control signal for locking and/or unlocking the locking mechanism of the mechanical orthotic joint.
Still other benefits and advantages of the invention will become apparent to those of average skill in the art upon a reading and understanding of the following detailed specification.